Declaring variable in excel template

Hello,
Can someone help me with the error message/issue i'm trying to solve with BIP excel template? I'm in need of declaring a varibale and using that as part of
loop to be incremented and display that valu outside the loop.

I was able to find lot of examples on how to declare and use varibales using functions like xdoxslt:set_variable($_XDOCTX,'V2','10') and xdoxslt:get_variable($_XDOCTX, 'V2')
in RTF templates, but none on how to make use of them in excel template.

So I tried to

1. create a declare varibale in excel template metadata sheet as